import math


def fun(x):
    return math.sin(x)-(x/2)**2

def fun_diff(x):
    return math.cos(x)-(x/2)


def newton(x,max_times,error):
    cnt=0
    while 1==1:
        cnt+=1
        new_x = x - fun(x) / fun_diff(x)
        if math.fabs(new_x-x)<error or cnt==max_times:
            break
        x=new_x
    return new_x

print("%.3f"%newton(2.0,500,0.0001))


